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NERVE AGENT ANTIDOTE AUTOINJECTOR KIT

Category: Medical

Topic: Toxicology

Level: EMR

Next Unit: Routes of Absorption

13 minute read

Organophosphate Poisoning

Most nerve agents are organophosphates, which cause parasympathetic (cholinergic) overactivation due to toxic blocking of the acetylcholinesterase receptors (thereby blocking the release of acetylcholinesterase: acetylcholine isn't broken down, resulting in a runaway cholinergic process that causes flooding of the airways with secretions, bronchoconstriction, and dangerous decreases in heart rate and blood pressure).

 

Nerve Agent Antidote Autoinjector Kits

Two types of nerve agent antidote autoinjector kits exist:

  1. Mark I
  2. DuoDote.

MARK I: The Mark I autoinjector kit contains two autoinjector syringes, each containing a separate drug.

  • The first drug in the Mark I system is atropine, and
  • the second drug is pralidoxime chloride.

DUODOTE: The DuoDote autoinjector kit contains one syringe that contains both atropine and pralidoxime chloride and was FDA-approved in 2007.

Nerve agent autoinjector kits should be administered to any rescuer that has serious signs or symptoms indicating the presence of nerve agent poisoning.

     

    2 Drugs Address Organophosphate Poisoning

    The two drugs in the antidote kits address the root of the problem in organophosphate poisoning by reactivating acetylcholinesterase.

    • ATROPINE is a parasympatholytic (anticholinergic): directly blocks the acetylcholine receptors. 
       
    • PRALIDOXIME CHLORIDE, also known as 2-PAM: indirectly blocks acetylcholine by reactivating acetylcholinesterase (the enzyme that breaks down acetylcholine). Thus, it doesn't counter the actions of organophosphate poisons like atropine does (i.e., trading cholinergic toxicity for its anticholinergic properties). Instead, pralidoxime binds with the organophosphate poison molecule where it's bound at the acetylcholinesterase receptor site, promoting the release of the toxin from that site, fully restoring acetylcholinesterase's function (i.e., cholinergic overactivity is defeated by a restored function of acetylcholinesterase. 

    Thus, atropine is an anticholinergic, whereas 2-PAM is an actual antidote.

    Administration to patients requires authorization from medical command.

    Nerve agent autoinjector kits should not be administered if only mild signs and symptoms of nerve agent poisoning, such as tearing or a runny nose are present. Keep in mind that the drugs in the nerve agent autoinjector kits have side effects:

    • ATROPINE increases heart rate, dries secretions, decreases gastric upset, and dilates pupils;
    • PRALIDOXIME CHLORIDE, also known as 2-PAM, may cause muscle twitching and difficulty breathing, which may mislead you to think the nerve agent poisoning is worsening. 

     

    Administration of Mark I Kit

    To administer the Mark I nerve agent autoinjector kit, the EMS provider should wear appropriate PPE, confirm that serious signs and symptoms of nerve agent poisoning are present, confirm the correct drug, and check the expiration date.

    After doing so, the EMS provider should

    1. grasp the atropine syringe,
    2. remove the protective yellow cap, and
    3. press the green end of the injector very firmly against the outer aspect of the patient’s upper leg (thigh) at a 90º angle and
    4. hold for 10 seconds.
    5. The EMS provider should check for the presence of a needle at the tip to ensure the drug was injected.
    6. After injection, the EMS provider should dispose of the syringe appropriately and then grasp the pralidoxime chloride syringe.
    7. The EMS provider should remove the gray protective cap,
    8. press the black end of the injector firmly against the outer aspect of the patient’s upper leg (thigh) at a 90º angle and
    9. hold for 10 seconds.
    10. The EMS provider should check for the presence of a needle at the tip to ensure the drug was injected, and then
    11. dispose of the syringe appropriately.
    12. As with any medication administration, the EMS provider should reassess the patient’s signs and symptoms.

     

    Administration of the DuoDote Kit

    To administer the DuoDote nerve agent autoinjector kit, the EMS provider should wear the appropriate PPE, confirm that serious signs and symptoms of nerve agent poisoning are present, confirm the correct drug, and check the expiration date.

    After doing so, the EMS provider should

    1. grasp the syringe with their dominant hand,
    2. remove the gray protective cap, and
    3. press the green (needle) end of the injector very firmly against the outer aspect of the patient’s upper leg (thigh) at a 90ºangle, and
    4. hold for 10 seconds.
    5. The EMS provider should check for the presence of a needle at the green tip to ensure the drug was injected and
    6. dispose of the syringe appropriately.
    7. As with any medication administration, the EMS provider should reassess the patient’s signs and symptoms.

     

    Age-Related Variations in Assessment and Management

    PEDIATRIC

    • Toddler-aged patients are prone to ingestion of toxic substances.
    • Adolescent patients are prone to experimentation with drugs of abuse which may be mistaken for specific poisonings.

    GERIATRIC: Medication errors in the geriatric population are common and may cause life-threatening conditions. Medications that are benign in younger populations can cause decreased mental status, abnormal vital signs, and other serious complications in the elderly.